Index: trunk/src/org/openstreetmap/josm/data/osm/Relation.java
===================================================================
--- trunk/src/org/openstreetmap/josm/data/osm/Relation.java	(revision 3154)
+++ trunk/src/org/openstreetmap/josm/data/osm/Relation.java	(revision 3155)
@@ -342,5 +342,8 @@
                 bbox = calculateBBox(new HashSet<PrimitiveId>());
             }
-            return new BBox(bbox);
+            if (bbox == null)
+                return new BBox(0, 0, 0, 0); // No real members
+            else
+                return new BBox(bbox);
         }
     }